Hydrazodisulfonate-positive halogen oxidizing agent systems for polymerization initiation



Patented Oct. 23, 1951 HYDRAZODISULFONATE-POSITIVE HALO- GEN OXIDIZINGAGENT SYSTEMS FOR POLYMERIZATION INITIATION Madison Hunt, Claymont,Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del.,a corporation of Delaware No Drawing. Application February 3, 1950,Serial No. 142,358

3 Claims.

This invention relates to the addition polymerization of polymerizableorganic compounds and more particularly to new polymerization catalystsystems.

Polymerization of ethylenically unsaturated compounds is a process ofgreat technical importance. Generally employed as polymerizationcatalysts are compounds containing directly linked oxygen atoms such asbenzoyl peroxide or potassium persulfate. In conventional polymerizationsystems, relatively high temperatures are required to obtain high ratesof conversion of the monomeric unsaturate to a polymer. The use ofelevated temperatures often leads to products of inferior qualities. Insome instances where appreciable rates of polymerization have beenachieved at lower temperatures, the products obtained have superiorphysical properties which areof substantial economic importance, suchas, for example, the increased abrasion resistance of synthetic rubbersprepared at temperatures which are low. Accordingly, new and improvedsystems of low temperature addition polymerization in high conversionare of considerable interest.

This invention has as an object the provision of a new process forpolymerizing addition polymerizable ethylenic compounds. Other objectswill appear hereinafter.

These obiects are accomplished by this invention wherein a monomersubject to addition polymerization by reason of a non-aromatic carboncarbon double bond is polymerized by bringing the same in contact with ahydrazodisulfonate and an oxidizing agent of the class consisting ofcompounds having halogen of positive valence of one.

The following examples in which parts are by weight are illustrative ofthe invention.

Example I sponding to an 83% conversion.

Example II When the general procedure of Example I was repeated exceptthat 0.35 part of calcium hypochlorite monohydrate (oxidizing agent inplace of the Dichloramine-T) was added slowly with stirring and thetemperature was C. and 84% yield of polymer was obtained.

Example III The general procedure of Example II was repeated except thatin place 0! the 220 parts of water, a mixture of 120 parts ethyl alcoholand 125 parts of water was used and the temperature was maintained at 30C. A*39% conversion of monomer to polymer was obtained. Under similarconditions but at 20 C., a yield was obtained.

Example IV The general procedure of Example I was repeated except that0.25 part or 1,3-dichloro-5,5- dimethylhydantoin (Dactin) was used asthe oxidizing agent and the polymerization time was one hour, a yield of50% of polymer was obtained.

Example V A glass vessel equipped with stirrer, thermometer, gas inlettube and Dry-Ice-acetone condenser system was charged with 150 parts ofwater, parts of absolute ethyl alcohol, 1.76 parts of pyridiniumhydrazodisulfonate, and, after cooling to 20 C. while the air wasflushed by oxygen-free nitrogen, a total of 15.7 parts of vinyl chloridewas introduced. The gas inlet tube was replaced by a dropping funnel andover a period of two hours, a total of 0.69 part of calcium hypochloritemonohydrate in 50 parts of water was added slowly with stirring. Afteran additiona1 30 minutes the polymer was removed by filtration. Therewas obtained 8.9 parts of polyvinyl chloride, corresponding to a 68%conversion. The polymer had a relative'viscosity of 1.110 as measured ona 0.1 g. sample in ml. of cyclohexanone.

Example VI When Example V was repeated except that the hypochloriteemployed was 3.24 parts of an 8% aqueous solution, there was obtained inone hour at 7 to -4 C., a 61% yield of polymer.

Example VII A glass vessel equipped with stirrer, thermometer, gas inlettube and condenser was charged with 56 parts of absolute ethyl alcohol,50 parts of water, 0.88 part of pyridinium hydrazodisulfonate, 15.6parts of vinyl chloride, and as oxidizing agent, 0.25 part of1,3-.dichloro-5,5-dimethyl hydantoin. After 1.5 hours at 25 C., therewas obtained a 49% conversion 01' monomer to polyvinyl chloride.

Example VIII A glass vessel was charged with 25 parts of methylmethacrylate, 80 parts of ethyl alcohol, parts of water, 0.88 part ofpyridinium hydrazodisulfonate, and 3.24 parts of an aqueous solutioncontaining 8% of hypochlorite ion as oxi- A vessel was charged with 12.5parts of methyl methacrylate, 48 parts of ethyl alcohol, 60 parts ofwater, 0.44 part of pyridinium hydrazodisul- 4 vinylpyridine, methylvinyl ketone and vinyl ethyl ether.

Polyfluoroethylenes including tetrafluoroethylene,chlorotrifluoroethylcne and 1,1-dichloro-23- Ionate and 0.125 part of1,3-dichloro-5,5-dimethylhydantoin as the oxidizing agent. After twohours at 25 0., a 75% conversion of monomer to polymer was obtained.

Example X When the general procedure of Example IX was repeated exceptthat 0.15 part 01 "Dlchloramine-T" was used as the oxidizing agent, a60% conversion 01' monomer to polymer was obtained in 1.5 hours.

Example XI Polymeri- Yield of Emulsion oxidizing Agent zation 'l imePolymer, Number (minutes) Per Cent 1 Hydrogen peroxide (6.7 parts of 14040 3% H50: 2 Sodium hypochlorite, 0.7 part of 140 83 a water solutioncontaining 4-5% active chlorine 3 Potassium persulfate 0.17 part... 14066 4 Potassium ferrlcyanidc 0.17 part. 140 75 The use of conventionalcatalysts such as persuli'ates, peroxides, or ferricyanides does notgive rise to significant amounts of polymer from chloroprene at l and 20C. Hydrogen peroxide and potassium persulfate will not give significantamounts of polymer at 5 C., during a two to three hour polymerization.Much longer times are required to effect polymerization with thesecatalysts.

The process of this invention is or generic application' to the additionpolymerization of polymerizable compounds having the non-aromatic orethylenic, C=C group. It is applicable to monomeric unsaturatedpolymerizable compounds in which the unsaturation is due to a terminalethylenic group which is attached to a negative radical. It is thusapplicable to polymerizable vinylidene compounds, including vinylcompounds and particularly preferred are those which contain the CH2=Cgroup.

Compounds having a terminal methylene which are subject topolymerization and copolymerization include olefins, e. g. ethylene andisobutylene; acrylyl and alkacrylyl compounds, e. g. acrylonitriie,methyl acrylate, ethyl methacrylate, methacrylic acid, methacrylamide;vinyl and vinyiidene halides; e. g. vinyl fluoride, vinylidene chloride;vinyl carboxylates, e. g., vinyl acetate, vinyl trimethylacetate; vinylimides, N-vinyllactams, e. g. N-vinylcaprolactam; vinyl aryls such asstyrene and other vinyl derivatives such as difluoroethylene may bepolymerized and copolymerized by the process of this invention.

Polymerizable compounds that have a plurality of ethylenic double bondsthat may be polymerized or copolymerized include those having conjugateddouble bonds, such as butadiene and 2-chlorobutadiene, and compoundswhich contain two or more double bonds which are isolated with respectto each other, such as ethylene glycol dimethacrylate, methacrylicanhydride, diallyl ,maleate and divinyl benzene.

In addition to copolymers obtainable from the classes of monomersmentioned above, the copolymerization of fumaric or malelc esters withtypes of monomers mentioned, may be effected by the process of thisinvention. Furthermore, the term polymerization is meant to includewithin its scope, in addition to the polymerization of a monomer aloneor of two or more monomers, i. e., copolymerization, the polymerizationof unsaturated monomer in the presence of a chain transfer agent, e. g.carbon tetrachloride. The latter has been called telomerization."

This invention is applicable to the polymerization of any unsaturatedcompound subject to addition polymerization by prior techniques. Optimumconditions may vary from monomer to monomer and since liquid phasepolymerization is desired, gases such as ethylene and propylene requirepressures.

The polymerizations are usually carried out at --40? C. to C. Althoughtemperatures may be lower, however the rate of polymerization isgenerally low. Higher temperatures, e. g., up to 100 C. or higher, maybe used, particularly when the time of polymerization is to be kept at aminimum, e. g., in a continuous process. Although this invention may bepracticed over a wide temperature range, optimum results are obtained atnot more than 40 C. and suitably 0-40 C. in liquid aqueous systems. Ingeneral, the time required for substantial polymerization depends uponother variables such as the specific temperature and concentrations ofmonomer,

catalyst, etc. Times of from a few minutes to 24 hours are customarilyemployed.

The polymerization may be carried out by conventional means. Liquidmedia in which the catalyst, monomer, and diluent are uniformlydispersed, such as solutions or emul ions, are pre- In general, anueoussystems are pre-.

ferred. ferred. For acrylonitrile nolymerizations, aqueous systems whichhave been adjusted to a pH of 2-6 with a halo en acid Fi e su er or pomers.

Anv hydrazodisulfonate salt which yields hydramdis lfonate ion under theconditions of polymerization, i. e.. an soluble hydrazodi ulfonate, maybe em loyed. The amount of hvdrazodisulfonate that is employed may varywidely. Generallv amounts of from 0.01 to 10% based on the weight ofmlvmerizable monomers are employed. It is generally convenient to employan alkali metal (sodium, potass um). ammonium or quaternary ammoni m(tetraethylammonium) salt of the hydrazodisultonate as the source of theion.

Not all oxidizing a ents may be employed. Th s sodium vanadate. sodiumselenate. potassium nerchlnrate. potassium chl rate, and potassiumnitrate had little or no effect. The examples are illustrative of theuse, with advantageous results, of compounds having halogen of effectivepositive valence of one. In view of ease of preparation and use thecompounds with positive monovalent halogen, e. g., the N-chlorocompounds, the hypohalites, and hypochlorites are generally preferred.The amount of oxidizing agent present is generally less than the amountof hydrazodisulfonate and may be present in much smaller amounts, e. g.from 0.001 to 50% of the amount of hydrazodisulfonate.

Polymerizations by the process of this invention give high conversion ofpolymer at 'low temperatures. The hydrazodisulfonate is a nonoxidizingmaterial and generally quite stable.

The foregoing detailed description has been given for clearness ofunderstanding only and no unnecessary limitations are to be understoodtherefrom. The invention is not limited to the exact details shown anddescribed for obvious modifications will occur to those skilled in theart.

What is claimed is:

1. Process for the polymerization of a monomer subject to additionpolymerization and containing an ethylenic double bond which comprisesbringing said monomer in contact, in an aqueous system, with a watersoluble hydrazodisulfonate and a compound containing positive monovalenthalogen. v

2. Process for the polymerization of a vinylidene monomer subject toaddition polymerization which comprises bringing said monomer incontact, in an aqueous system, with a water soluble hydrazodisulfonateand a compound containing positive monovalent halogen.

3. Process for the polymerization of a vinyl monomer subject to additionpolymerization which comprises bringing said monomer in contact, in anaqueous system, with a water soluble hydrazodisulfonate and a compoundcontaining positive monovalent halogen.

MADISON HUNT.

REFERENCES CITED The following references are of record in the file ofthis patent: V

UNITED STATES PATENTS Number Name Date 2,429,060 Hoover et al. Oct. 14,1947 FOREIGN PATENTS Number Country Date 333,894 Great Britain Aug. 18,1930 OTHER REFERENCES Mellor, vol. VIII, Comp. Treat of Inorg. andTheoretical Chem., pages 682-683, Longmans, N. Y. 1928.

1. PROCESS FOR THE POLYMERIZATION OF A MONOMER SUBJECT TO ADDITIONPOLYMERIZATION AND CONTAINING AN ETHYLENIC DOUBLE BOND WHICH COMPRISESBRINGING SAID MONOMER IN CONTACT, IN AN AQUEOUS SYSTEM, WITH A WATERSOLUBLE HYDRAZODISULFONATE AND A COMPOUND CONTAINING POSITIVE MONOVALENTHALOGEN.